Firstly,
let's assume that the Image will appear as a jpeg for viewing on a web page at
around 700 pixels wide. At 72ppi this gives a .PSD file of around 1mb before converting
to jpeg. The 'Layer Style' settings below refer to a file of about this size

Starting
Image (Worcester Cathedral)

Set
Black as the Foreground colour then use the 'Type Tool' to apply the required
text.

Change
the 'Blend mode' for the Type Layer to 'Lighten' - the text disappears!

To
reveal the text, we need to create a 'Layer Style'.

The
'Layer Style icon

Click
on the 'f', Layer Style, icon at the base of the Layers Palette (see 'screen grab'
below). From the drop-down menu, choose 'Bevel & Emboss'. In the Layer Style dialogue
box that opens try these settings as a starting point:

Experiment
using other options in the dialogue box such as Inner Glow, Outer Glow, Stroke,
etc. Changing these settings may improve the appearance of your text - it all
depends upon what you need and picture content.